Ch 17: Blood Flashcards
What is the blood comprised of?
- Plasma
- WBC
- RBC
- Platelets
What are the 3 layers of spun blood?
- Plasma
- RBC
- WBC
How much of the blood is plasma?
55%
How much of the blood are erythrocytes?
45%
How much of the blood are the buffy coat?
less than 1%
What is hematocrit?
Percent of blood volume that is RBCs
Describe the physical characteristics of blood
Sticky, opaque with metallic taste
How does the color of blood vary in the presence of O2?
High O2: scarlet
Low O2: dark red
What is the normal pH of blood?
7.35-7.45
How much does blood take up body weight?
8%
What is the standard volume of blood in males and females?
Males: 5-6L
Females: 4-5L
How much water is in blood plasma?
90%
What are the components of plasma?
- Dissolved solutes
- 60% albumin
- 36% globulins
- 4% fibrinogen
Where is plasma produced?
Liver
What are the functions of albumin?
- Substance carrier
- Blood buffer
- Major contributor of plasma osmotic pressure
Why are WBCs the only complete cell of the blood?
RBCs have no nuclei or organelles, and platelets are cell fragments
Describe the distribution functions of the blood?
- Delivering O2 and nutrients to body cells
- Transporting metabolic wastes to lungs and kidneys for elimination
- Transporting hormones from endocrine organs to target organs
Describe the regulation functions of the blood?
- Maintaining body temperature by absorbing and distributing heat
- Maintaining normal pH using buffers; alkaline reserve of bicarbonate ions
- Maintaining adequate fluid volume in circulatory system
Describe the protection functions of the blood?
- Preventing blood loss: platelets and clotting
2. Preventing infection: antibodies, WBCs
Describe the structure of erythrocytes
- Biconcave discs
- Anucleate
- No organelles
- Filled with Hb
- Contain plasma membrane protein spectrin
Describe the structure of erythrocytes that contribute to gas transport
- Biconcave shape give huge suface area relative to volume
- > 97% Hb
- No mitochondria or ATP production anaerobic so it doesn’t consume O2
What is the major contributing to blood viscosity?
RBCs
What is the function of RBCs?
- RBCs dedicated to respiratory gas transport
2. Hb binds reversibly with O2
Describe the components of Hemoglobin
- Globin: 2 alpha and 2 beta polypeptide chains
- Heme pigment bond to globin
- Heme iron center binds to 1 O2
How many Hb molecules are in a single RBC?
250 million
How many O2 molecules are transported by a single Hb?
4
What occurs during O2 loading?
Production of oxyhemoblobin
Where does O2 loading occur?
Lungs
What occurs during O2 unloading?
Production of deoxyhemoglobin or reducing Hb
Where does O2 unloading occur?
Tissues
What occurs during CO2 loading?
Formation of carbaminohemoglobin
Where doe CO2 loading occur?
Tissues
What is hematopoeisis?
Blood cell formation in red bone marrow
What is the purpose for hematopoietic stem cells?
- Give rise to all formed elements
- Hormones and growth factors push cell toward specific pathway of blood cell development
- Committed cells cannot change
What occurs when there are too many RBCs?
Hypoxia
What occurs when there are too few RBCs?
Hypoxia
What dictates RBS production and destruction?
- Hormonal controls
2. Adequate supplies of Fe, amino acids, and Vitamin B
What controls the production of RBC hormonally?
EPO
Where is is EPO released from?
Released by kidneys in response to hypoxia
What hormone can enhance EPO production?
Testosterone causing higher RBC counts
What are the 3 factors that cause hypoxia?
- Decreased RBC numbers due to hemorrhage or increased destruction
- Insufficient hemoglobin per RBC (e.g., iron deficiency)
- Reduced availability of O2 (e.g., high altitudes)
Describe the mechanism to restore homeostasis of blood from hypoxia
- Hypoxia occurs
- Kidney releases EPO
- EPO stimulates red bone marrow
- Increase in RBC count
- O2 carrying ability of RBC rises
What types of dietary requirement are used for erythropoiesis?
- Nutrients
- Iron
- Vitamin B12 and folic acid
What is the life span of RBCs?
100-120 days
What occurs when heme and globin are separated?
- Iron is salvaged for reuse
- Heme degraded to bilirubin
- Liver secretes bilirubin which is degraded by urobilinogen and pigment leaves body in feces as stercobilin
- Globin metabolized into amino acids
What happens to RBCs when they get old?
- Become fragile, Hb begins to degenerate
- Gets trapped in spleen
- Macrophages engulf dying RBCs in spleen
Describe the lifetime of a RBC
- Low O2 levels in blood stimulate kidneys to produce EPO
- EPO levels rise in blood
- EPO promote RBC formation in red bone marrow
- Aged and damagesd are engulfed by macrophages and secreted in feces or raw materials are recycled
What is anemia?
Blood having abnormally low O2 carrying capacity
What are the symptoms of anemia?
- Fatigue
- Pallor
- Shortness of breath
- Chills
What causes anemia?
- Blood loss
- Low RBC production
- High RBC destruction
Describe how blood loss can cause anemia?
Hemorrhaging
Describe how Low RBC production can cause anemia
- Iron deficiency
- Pernicious anemia: Autoimmune deficiency in B12
- Aplastic anemia: desctruction of red marrow
Describe how high RBC destruction can cause anemia
- Hemolytic anemia: Premature RBC lysis due to abnormal Hb
- Thalassemia: genetic deficiency of Hb
- Sickle cell anemia
What is polycythemia vera?
- Bone marrow cancer → excess RBCs
2. Severely increased blood viscosity
What is secondary polycythemia?
- Less O2 available (high altitude) or EPO production increases → higher RBC count
- Blood doping
How does sickle cells differ from normal RBCs?
- Hemoglobin S
- RBC is crescent shape where unloading O2 is low
- RBCs rupture easily and block small vessels
What causes sickle cell anemia?
Glutamate side chain is substituted with valine
What occurs when a person has 2 copies of the sickle-cell gene?
Sickle-cell anemia
What occurs when a person has 1 copy of the sickle-cell gene?
Milder disease and better chance of surviving malaria
How much of the WBC make up the total blood volume?
Less than 1%
What are the functions of WBC?
- Can leave capillaries via diapedesis
2. Move through tissue spaces by ameboid motion and positive chemotaxis
What is leukocytosis?
Increased count of WBC in response of an infection
What are the 2 categories of WBC?
- Granulocytes
2. Agranulocytes
What are granulocytes?
- Visible cytoplasmic granules
2. Lobed nuclei
What are the types of granulocytes?
- Neutrophils
- Eosinophils
- Basophils
What are neutrophils?
- Most numerous WBCs
- Granules contain hydrolytic enzymes or defensins
- Very phagocytic—”bacteria slayers”
What are eosinophils?
- Granules lysosome-like
- Release enzymes to digest parasitic worms
- Role in allergies and asthma
- Role in modulating immune response
What are basophils?
- Contains histamines
2. Function similar to mast cells
What are histamines?
Inflammatory chemical that acts as vasodilator to attract WBCs to inflamed sites
What are agranulocytes?
- No visible cytoplasmic granules
2. Have spherical or kidney-shaped nuclei
What are the types of agranulocytes?
- Lymphocytes
2. Monocytes
What are lymphocytes?
- 2nd most numerous WBC
- Found in the lymphoid tissue
- Crucial to immunity
What are the types of lymphocytes?
- T cells
2. B cells
What are T cells?
Act against virus-infected cells and tumor cells
What are B cells?
Give rise to plasma cells which produce antibodies
What are monocytes?
- Largest leukocytes
- Enter tissue and differentiate into macrophages
- Actively phagocytic cells; crucial against viruses, intracellular bacterial parasites, and chronic infections
- Activate lymphocytes to mount an immune response
What is the production of WBCs called?
Leukopoiesis
What are the chemical messengers that stimulate WBC production?
- Interleukins
2. Colony-stimulating factors
What is leukopenia?
Abnormally low WBC count
What is leukemia?
Cancer → overproduction of abnormal WBCs
What is infectious mononucleosis?
- Caused by the Epstein-Barr virus
- High numbers of atypical agranulocytes
- Tired, achy, chronic sore throat, low fever
What are platelets?
Cytoplasmic fragments of megakaryocytes that form temporary platelet plugs to seal blood vessels
What regulates platelet formation?
Thrombopoeitin
How are platelets stay inactive?
Nitric oxide and prostacyclin
When would platelets degenerate?
10 days
Is a thrombocytes a platelet?
Yes
What is hemostasis?
Fast series of reactions for stopping bleeding
Describe the steps of hemostasis
- Vascular spasm: smooth muscle contracts causing vasoconstriction
- Platelet plug formation: injury to lining of vessel exposes collagen fibers, platelets adhere
- Platelets release chemicals that make nearby pllatelets sticky, forming platelet plug
- Coagulation: fibrin forms a mesh that traps RBCs and platelets forming clots
What are the triggers for vascular spasm in hemostasis?
- Direct injury to vascular smooth muscle
- Chemicals released by endotheilial cells and platelets
- Pain reflexes
What is the von Willebran factor?
Platelets stick to collagen fibers via plasma protein
What happens to a platelet when the plug forms?
- Swell
- Spiked
- Sticky
- Release chemical messengers
What kind of chemical messengers are released by platelets during clotting?
- ADP
2. Seratonin and thromboxane
How does ADP help clotting?
Causes more platelets to stick and release contents
How do Seratonin and thromboxane help clotting?
Enhance vascular spasm and platelet aggregation
What are the phases of coagulation?
- Prothrombin activator formed in both intrinsic and extrinsic pathways
- Prothrombin converted to enzyme thrombin
- Thrombin catalyzes fibrinogen to fibrin
Describe phase 1 of coagulation
- Triggered by tissue damage events
- Involve a series of procoagulants
- Each pathway cascades toward factor X
- Factor X complexes with Ca2+, PF3, and factor V to form prothrombin activator
What is the intrinsic pathway?
- Triggered by negatively charged surfaces (activated platelets, collagen, glass)
- Uses factors present within blood (intrinsic)
What is the extrinsic pathway?
- Triggered by exposure to tissue factor (TF) or factorIII (an extrinsic factor)
- Bypasses several steps of intrinsic pathway, so faster
Describe phase 2 of coagulation
- Prothrombin activator catalyzes transformation of prothrombin to activate thrombin
- Once activator is formed, clots form in 10-15 seconds
Describe phase 3 of coagulation
- Thrombin converts soluable fibronogen to fibrin
2. Thrombin with Ca2+ activates facotr XIII which cross-links fibrin and strengthens and stabilizes clot
What occurs during clot refraction?
- Stabilizes clot
- Actina and myosin in platelets contract withing 30-60 minutes
- Contraction pulls on fibrin stands, squeezing serum from clot
- Draws ruptured blood vessel edges together
What hormones drive vessel repair?
- Platelet derived growth factor (PDGF)
2. Vascular endothelial growth factor (VEGF)
What does the PDGF stimulate?
Division of smooth muscle cells and fibroblasts to rebuild blood vessel wall
What does the VEGF stimulate?
Endothelial cells to multiply and restore endothelial lining
What is fibrinolysis?
The removal of unneeded clots after healing
What occurs during fibrinolysis?
Plasminogen in clot is converted to plasmin by tPA, fator XII, and thrombin
What enzyme digests fibrin?
Plasmin
What are the 2 mechanisms that limit clot size?
- Swift removal and dilution of clotting factors
2. Inhibition of activated clotting factors
What binds to fibrin threads?
Thromobin
What inactivates unbound thrombin?
Antithrombin III
What inhibits thrombin by enhancing antithrombin III?
Heparin
What prevents platelet adhesion?
- Smooth endothelium of blood vessels prevents platelets from clinging
- Antithrombic substances nitric oxide and prostacyclin secreted by endothelial cells
- Vitamin E quinone acts as potent anticoagulant
What is thrombus?
Clot that develops and persists in unbroken vessel
What is an embolus?
Thrombus freely floating in blodstream
What is an ebolism?
Embolus obstructing a vessel
What are the risk factors of undesirable clotting?
- Atherosclerosis
- Inflammation
- Slowly flowing blood or blood stasis from immobility
What is thrombocytopenia?
Deficient number of circulating platelets
What is hemophilia A, B, and C?
Prolonged bleeding disorder
What is impaired liver function?
- Inability to synthesize procoagulants
- Causes include vitamin K deficiency, hepatitis, and cirrhosis
- Impaired fat absorption and liver disease can also prevent liver from producing bile, impairing fat and vitamin K absorption
What is DIC?
- Clotting causes bleeding
- Widespread clotting blocks intact blood vessels
- Severe bleeding occurs because residual blood unable to clot (due to consumption of platelets)
When would you uses whole-blood transfusions?
Blood loss both rapid and substantial
When would you uses packed-blood transfusions?
To restore oxygen-carrying capacity
What is the role of antigens in RBC?
- Anything perceived as foreign; generates an immune response
- Promoters of agglutination; called agglutinogens
What happens when blood transfers are mismatched?
- May be agullated and destroyed
2. Can be fatal
What are the antigen classifications of RBC?
- ABO
2. Rh
What are agglutinins?
Anti-A or B antibodies
How are Rh factors inherited?
Anti-Rh antibodies form if Rh– individual receives Rh+ blood, or Rh– mom carrying Rh+ fetus
What is erythroblastosis fetalis?
Only occurs in Rh– mom with Rh+ fetus
What is RhoGAM?
Serum containing anti-Rh can prevent Rh- mother from becoming sensitizes
What heolytic disease can occur during the second pregancy?
Mom’s anti-Rh antibodies cross placenta and destroy RBCs of Rh+ baby
What is donor’s cells?
- Attacked by recipient’s plasma agglutinins
- Agglutinate and clog small vessels
- Rupture and release hemoglobin into bloodstream
What are the results of donor’s cells?
- Diminished oxygen-carrying capacity
- Diminished blood flow beyond blocked vessels
- Hemoglobin in kidney tubules → renal failure
What are the treatments for donor’s cells?
Preventing kidney damage by flushing fluids and diuretics to wash out hemoglobin
What is the universal donor?
O becuase no presence of A or B antigens
What is universal recipient?
AB because they contain no anti-A or anti-B antibodies
What is the term for patients pre-donating blood?
Autologous transfusion
How is blood typing achieved?
- Mixing RBCs with antibodies against its agglutinogen(s) causes clumping of RBCs
- Done for ABO and for Rh factor
How is blood cross matching achieved?
- Mix recipient’s serum with donor RBCs
2. Mix recipient’s RBCs with donor serum
What can occur when a person has extremely low blood volume?
Death from shock
How is volume replenished when extreme blood loss occurs?
- Normal saline or multiple-electrolyte solution (Ringer’s solution) that mimics plasma electrolyte composition
- Plasma expanders
What are platelet expanders?
- Mimic osmotic properties of albumin
2. More expensive and may cause problems
What tests for anemia?
Hematocrit
What tests for diabetes?
Blood glucose tests
What is the purpose of microscopically examining blood?
- Reveals variations in size and shape of RBCs, indications of anemias
- Differential WBC count
How can we assess hemostasis?
Prothrombin time and platelet counts
What is SMAC?
Blood chemistry profile for kidney and liver disorders
What does a complete blood count achieve?
Checks formed elements, hematocrit, and hemoglobin